Abnormal direct entry of the umbilical vein into the right atrium: antenatal detection, embryologic aspects.

Abnormal direct umbilical venous return into the right atrium was detected at obstetric ultrasonography in a 23 week fetus. This was an isolated anomaly; the growth of the fetus and size of the liver were normal, and the child was normal on examination at birth. Exclusion of the umbilico-placental circulation brought about closure of the umbilical vein. Growth and development of the child were normal 6 months after birth. Five other cases of abnormal umbilical venous entry into the right atrium have been reported in the literature, but associated with severe malformations, with situs ambiguous and heterotaxy. These cases have been grouped under the heading: persistence of the right umbilical vein. In view of recent findings relating to the organogenesis of the veins of the human liver, it seems preferable to label this anomaly: direct umbilical venous return into the right atrium.